1. Field of the Invention
This invention relates to a steering-rack-equipped auxiliary power steering, especially for motor vehicles. In this kind of auxiliary power steering, a pinion is positioned rotatably in a steering housing. A steering rack is guided in an axially movable fashion in the steering housing and is maintained so as to engage the pinion by means of a spring-loaded thrust piece. A servomotor is used to support the auxiliary power steering; this servomotor is connected with the steering rod in a driving manner. A control device for steering a pressure agent to and from the servomotor can be adjusted as a function of a movement of the pinion.
2. Description of the Prior Art
Such a steering-rack-equipped auxiliary power steering is known from EP-B1-01 92 641. In this design, tile oblique gearing of the pinion generates a force component upon the pinion in an axial direction so that the pinion will be adjustable in an axial direction. The control valves can be adjusted by means of this axial shifting of the pinion.
To ensure perfect operation of the control valves, the slope angle of the pinion should, if at all possible, be more than 35 degrees. In that way, the choice of pinion gearing is heavily restricted. The activation of the control valves can be impaired in that the lateral forces that act upon the steering rack are braced upon the pinion and call thus increase the friction for the axial shifting of the pinion. The known steering-rack-equipped auxiliary power steering can then not be used when only a limited structural space is available in the area of the diameter of the pinion housing.
The purpose of the invention is to prevent the described shortcomings without any additional design effort. In particular, it should be possible to use pinions with differing helix angles slope angles!, in other words, also with helix angles of less than 35 degrees.